Process of refining white oil



Patented Nov. 24, 1942 PROCESS OF REFINING WHITE 01L Albert P. Giraitis,Maplewood, N. J., assignor to Standard Oil Development Company, acorporation of Delaware No Drawing. Application February 6, 1940,

Serial No. 317,561 k Claims. (01. 196-40) This invention relates to thepreparation of stable highly refined mineral oils with special regard tothe treatment of white oil products to effect an improvement instability.

In the preparation of white oil products the base stock is usually adistillate derived from a Mid-Continent type or a Gulf Coast type crude.The distillate is normally subjected to exhaustive sulfuric acidtreatment, that is, to treatment with sulfuric acid of concentrations incase of distillates of lubricating oil consistency between 96% strengthand 30% fuming acid and with volumes relative to the oil of between and50% and in the case of distillates of the kerosene and naphtha boilingranges, between 96% strength and fuming acid and with volumes relativeto the oil of between 5% and The in a single application, it being moreusual to efiect the treatment in stages with small quantities of acidand separation of the sludge so formed before the next addition of acid.After the removal from the oil of the acid sludge, the oil isneutralized. The neutralization is usually elfected by a 5% to alkalisolution of either caustic soda or sodium carbonate applied in a singlebatch or as a stream in continuous treatment. The neutralized oil isthen washed especially in the case of the heavier white oils to removesulfonate soaps, preferably with a wateralcohol mixture, and then blownwith steam and then air to remove traces of alcohol and Water, if suchare considered objectionable in the final product. Sometimes the oil isfinished by a clay treatment to efiect an improvement in color..

The products of such processing are often chemically unstable resultingin the development during storage of corrosive compounds, garlic-likeodors and unpleasant tastes, any of which changes are commerciallyobjectionable.

In the present invention the oil distillate is,

as previously, exhaustively treated with sulfuric acid, the sludgeseparated and the oil phase neutralized with an alkali solutionpreferably of 0% sodium carbonate, the alkaline solution separated, andthe oil if sulfonate soaps are present, washed, preferably with awater-alcohol mixture such as of ethyl or isopropyl alcohol, to removethe soaps and the alcohol and moisture removedby blowing steam and thenair through the oil. 'If an improvement in color is desired the productmay be subsequently clay treated. In treating the oils of the keroseneand. naphtha boiling ranges, the steps of washing with aqueous alcoholicmixtures after neutralization and treating with clay are usuallyconsidered unnecessary. Upon such highly refined oils the process of thepresent invention may be applied to effect a chemical stabilizationespecially with regard to overcomingthe development of corrosivecompounds, de-

terioration of color and objectionable odors and tastes.

The process is to treat the highly refined oil with a dry alkaline earthbasic reacting compound either alone or in the presence of adecolorizing material such as clay. It has been found that when thealkaline earth basic reacting compound material is very finely divided,such as after treatment in a ball mill for about eighteen hours, muchsmaller quantities can be used to effect similar treating results. Bythe use of the term alkaline earth the broad significance of the term isintended to be conveyed, namely, to cover the oxides, the hydroxides andcarbonates of the di-basic alkaline earth metals which specifically aremagnesium, calcium, strontium and barium. Normal atmospherictemperatures are usually employed when the oils are treated with thealkaline earth material by percolation or filtration methods. Elevatedtemperatures are preferably employed when the oils are treated with thealkaline earth basic reacting compound by contact methods.

Avery convenient method of processing the oils according to the presentinvention is to pass the oils at atmospheric temperatures throughpercolation filters containing the alkaline earth basic reactingcompound admixed with clay. Also convenient is the method of processingthe oils at atmospheric temperatures by first preparing a concentratedslurry of the alkaline earth basic reacting compound with a portion ofthe untreated oil and then treating, the remaining portion of the oilwith the slurry so prepared. Another advantageous manner of processingis to pass the oil to be treated together with pulverizedalkaline earthbasic reacting compound tical purposes the development of objectionableodors and corrosive compounds.

It is appreciated that the alkaline earths have been previously employedin treating petroleum oils. The uses in the past have been mainly inconnection with those of aqueous solutions and aqueous suspensions ofthe materials and for the treatment of crude stocks for purposes ofneutralization and the removal of hydrogen sulfide. As refining agentstheir uses have been somewhat limited because of their relatively lowsolubilities in water and because of the development in many cases oftreating emulsions due to the formation of sulfonate soaps which arepotent. emulsifiers. It is believed the present invention is the firstsatisfactory process involving the use of the alkaline earths in anessentially dry state for the refining of high-grade petroleum productsof which the white oils may be cited as examples. The action of thealkaline earths on highly refined oils in the absence of an aqueousphase is specific and is not paralleled by a similar activity of themono-basic caustic alkalis. The alkaline earths when employed inaccordance with the methods of, the present invention react with, andremove, the undesirable constituents from highly refined stocks whichcause in these neutralized and doctor sweet oils, color and odordeterioration and the development of corrosive compounds. the presentinvention are the only satisfactory treating, methods so far developedfor effecting this improved stability of highly refined petroleumproducts.

In the preparation of such highly refined petroleum products as thewhite oils one of the most important controlling tests is that ofdetermining under specific conditions corrosion to the copper strip. Inthis test a copper strip is mechanically polished with an inert abrasivematerial such as Tripoli powder on a dampened reclaimed towel or othercloth material free from sizing. The strip is freed of the abrasivematerial first by dusting with a clean dry cloth and then wiping withfilter paper. The size of the copper strip which is employed isconvenient for placing in a four ounce sample bottle, that is, stripsmeasuring /2" x 3". The polished strip is then placed in a clean dryfour ounce bottle, containing sufficient oil to immerse completely thestrip. The bottle is stoppered with a clean cork and placed in aconstant temperaturebath at a temperature of 210 F. for two hours. Atthe end of the two-hour period the sample is removed from the bath andthe appearance of the copper strip compared with the appearance of asimilarly polished copper strip which has been heated in an adjacentfour ounce bottle containing air. The presence of corrosive substancesin the oil sample is indicated by the difference in discolorationbetween the copper strip immersed in the oil sample and on the blankcopper strip. The results are reported as:

(1) Same as blank Pass #1 (2) Slight reddish discoloration Pass #2 (3)Definite reddish discoloration Does not pass #3 (4) Reddishdiscoloration with slight iridescence or brassy appearance Does not pass#4 (5) E x t e n s i V e iridescent,

brassy or black discoloration Does not pass #5 It is believed that theprocedures of g The following examples will serve to illustrate theinvention. The invention, however, is not limited by the followingexamples which are merely presented for purposes of illustration:

Example 1 One liter of oil which had been treated with 32% of its volumeof fuming sulfuric acid and had a viscosity of 55 seconds SayboltUniversal at 100 F., and neutralized with 10% aqueous caustic sodasolution, washed with a 50-50 water-isopropyl alcohol mixture, blownwith steam to remove traces of alcohol and contacted immediately with 20grams of unburnt fine Attapulgus clay for 20 minutes at 70 C. Then gramsof hydrated lime was added and the treatment continued for 40 minuteslonger. After the removal of the solid material by passing themixture-through a blotter press a colorless oil was obtained having apass No. 2 copper strip test. A sampleof the same oil but not treatedwith the hydrated lime was finished in the regular way by percolationthrough granular clay gave a No. 5 copper strip test.

Example 2 A liter of oil'which had been treated with 40% of its volumeof 20% fuming sulfuric acid and of viscosity of 340 Saybolt Universalseconds at 100 F. was neutralized with 10% aqueous caustic sodasolution, washed with an aqueous alcoholic (40% isopropyl) solution,blown with steam to remove traces of alcohol then contacted with 20grams of unburnt fine Attapulgus clay for 20 minutes, at 70 C., andsubsequently with 20 grams of hydrated lime for an additional period of40 minutes. The mixture was then passed through a blotter press and theoil filtrate percolated through grams of 30 tomesh Attapulgus clay in a1" glass filter at room temperature. The oil after this treatment gave apass No. 1 copper strip test. A second sample of the oil treated asabove except for the contacting with the hydrated lime gave a No. 4copper strip test.

Example 3 A liter of oil which had been treated with 32% of its volumeof 20% fuming sulfuric acid and had a viscosity of 50 Saybolt Universalseconds at 100 F., was neutralized with a 10% aqueous solution of sodiumcarbonate, washed with a 50-50 water-isopropyl mixture, blown with steamto remove traces of alcohol,. then percolated through a bed of grams of30 to 60 mesh bauxite in a 1" glass filter tube containing 20 grams of30 to 60 mesh hydrated lime in a layer one inch from the bottom of thefilter. This percolation treatment was carried out at room temperature.The percolated oil gave a pass No. 2 copper strip test. Previous topercolation the oil gave a. No. 5 test and when filtered through gramsof bauxite alone gave a No. 4 copper strip test.

Example 4 A liter of oil treated with 30% of its volume of 20% fumingsulfuric acid and of viscosity of 345 Saybolt Universal seconds at 100F. was neutralized with 10% aqueous sodium carbonate solution, washedwith a 50-50 water-isopropyl alcohol mixture, blown with steam to removealcohol, and then percolated through a bed of granular clay. The oil wasthen contacted at 70 C. with 2.5 grams of powderedmagnesia for one houremploying air as a means of agitation.

exposure to the mercury vapor lamp.

Whatis claimed is:

After-the removal of-the solid'magnesia by filter- 1. The process ofrefining white oils'which ing through paper, the oil gave a- No. 1 passcopper test and did not develop a garlic odor after exposure to the raysof amercury vap'or lamp for eight hours;

and developed agarlic odor after six hours The magnesia on the filterpaper was used again with equal efiect in the treatment of an-' Example5 40 gallons of oil which had been previously treated with 32% of itsvolume of 20% fuming sulfuric acid and had a viscosity of 50 SayboltUniversal seconds at 100 F. was neutralized with a aqueous sodiumcarbonate solution washed with a 50-50 water-isopropyl alcohol mixture,blown with steam to remove traces of alcohol and percolated through abed of granular clay, and then contacted with sixteen pounds of hydratedlime at room temperature, using a stream of air for agitation. Samplesof the oil taken immediately after the addition of the lime and for eachof the four hours following gave pass No. 2 copper tests. The originaloil previous to the lime treatment gave a No. 5 copper test.

As a corollary, it was found that when 0.25% by weight of lime ground ina ball mill for about eighteen hours was employed at 70 C. as thealkaline earth agent, the oil gave a pass No. 1 copper test.

In addition to lime and magnesia the carbonates of calcium and magnesiumhave been' found to be very effective treating reagents, and in certaincases a calcium hypochlorite has been found to be very satisfactory.Hydrated lime has been found to be more satisfactory than anhydrouslime. The oxides, hydroxides and carbonates of strontium and barium areeffective treating reagents but less extensively employed because oftheir higher cost.

I Previous to treatment with magnesia the oil gave a No. 3 copper testIt has been found that the treatment with the alkaline earth basicreacting compounds of the neutralized white oils and of the white oilsafter clay treating, improves the stability of the treated products withregard to the odor, color and taste as well as minimizing thedevelopment of corrosive compounds. It has been found that oils whichare improved by the process of this invention with regard to the copperstrip test also show similar degrees of improvement and resistance tothe development of objectionable odors. Highly refined oils in thenaphtha and kerosene boiling ranges used in the preparation of solvents,lacquers and spray compositions may also be treated to advantage withthe alkaline earths according to the methods of the present invention inorder to improve the color, odor, resistance to the formation ofcorrosive compounds and, in general, the stability of these materials,

While the invention has been described in detail and a number ofillustrative examples have been given, it is to be understood that theinvention is not limited thereby but same have been given for purposesof conveying an appreciation of the scope and nature of the invention.It will be obvious to those skilled in the art that variations of theprocess can be made within the spirit of the invention.

comprises exhaustively treating a petroleum oil with concentratedsulfuric acid, separating the sludge, neutralizing the oil with analkaline solu- 'dry alkaline earth basic reacting compound. 10

which comprises exhaustivelytreating a petro- 2. The process of refiningmineral white oils leum oil of lubricating oil consistency withconcentrated sulfuric acid,- separating the sludge,

then neutralizing the'oil with an aqueous alkali solution, separatingthe aqueous solution, washing the oil with a water-isopropyl alcoholmixture, treating the oil with steam and then with air to remove tracesof isopropyl alcohol and water, treating the oil with clay and thenchemically stabilizing the oil by treating with a dry alkaline earthbasic reacting compound.

3. The process of refining mineral white oils which comprisesexhaustively treating a petroleum oil of lubricating oil consistencywith concentrated sulfuric acid, separating the sludge, thenneutralizing the oil with an aqueous alkali solution, separating theaqueous solution, washing the oil with a water-isopropyl alcohol mix- I,ture, treating the oil with steam and then with air to remove traces ofisopropyl alcohol and water, contacting the oil with clay and thenchemically stabilizing the oil by treating with an alkaline earth basicreacting compound.

4. The process of refining mineral white oils which comprisesexhaustively treating a petroleum oil of lubricating oil consistencywith concentrated sulfuric acid, separating the sludge, thenneutralizing the oil with an aqueous alkali solution, separating theaqueous solution, washing the oil with a water-isopropyl alcoholmixture, treating the oil with steam and then air to remove traces ofisopropyl alcohol and water, contacting the oil with clay, and thenchemically stabilizing the oil by treating with an alkaline earth basicreacting compound separating from the resultant mixture the clay andalkaline earth basic reacting compound and then percolating the thuspurified oil through clay.

5. The process according to claim 4 in which the alkaline earth basicreacting compound employed is lime.

6. The process according to claim 4 in which the alkaline earth basicreacting compound employed is magnesia.

7. The process of refining mineral white oils which comprisesexhaustively treating a petroleum oil of lubricating oil consistencywith concentrated sulfuric acid, separating the sludge, thenneutralizing the oil with aqueous alkali, separating the,aqueous'solution washing the. oil with a water-isopropyl alcoholmixture,treating the oil with steam and subsequently with air to remove tracesof isopropyl alcohol and water, and stabilizing the oil by percolatingthrough alkaline earth basic reacting compound admixed with clay.

8. The process of refining mineral white oils which comprisesexhaustively treating a petroleum oil of lubricating oil consistencywith concentrated sulfuric acid, separating the sludge, thenneutralizing the oil with an aqueous alkali solution, separating theaqueous solution, washing the oil with a water-isopropyl alcoholmixture, treating the oil with steam and subsequently with whichcomprises exhaustively treating a petroleum oil of lubricatingoilconsistency with concentrated sulfuric acid, separating the sludge, thenneutralizing the oil'with anaqueous alkali solution, separating the.aqueous solution, wash-' ing the oil with a-water-isopropyl alcoholmixture, treating the oil with steam and then-air to remove traces ofisopropyl-alcohol and water, then saibilizing the oil by percolatingthrough clay admixed with magnesia.

10. The-process ofreflning mineral white-oils which comprisesexhaustively treating a petroleumcilof lubricating oil consistency withconcentrated sulfuric acid, separating the sludge,

then neutralizing the oil with an aqueous -alkali solution,separatingthe aqueous solution, washing the oil with a water-isopropylalcohol solution, treating the washed oil with steam and then air toremove traces of isopropyl alcohol and water, then stabilizingthe oilbypassing together with pulverized alkaline earth basic reacting compoundthrough a colloid-mil1,.and separating the solid material fronrthe oil.I

- ALBERT P.GIRAITIS.

